Fluid switching device

Claim 1

A fluid switcHing device comprising: a main body defining therein a cavity of a substantially Ishaped cross section containing a pair of opposed first chambers and an output chamber which communicates at its ends with said first chambers, a diaphragm disposed in each of said first chambers to partition the same into an outside pressure chamber and an inside pressure chamber communicating with said output chamber, said main body having four input ports each opening into a respective one of said outside and inside pressure chambers and an output port provided for said output chamber, a valve mechanism operatively connected to said diaphragms for selectively switching fluid communication between said output chamber and one of said inside pressure chambers in response to displacement of said diaphragms, a pilot body coupled with said main body and defining therein a second chamber adjacent to one of said outside pressure chambers, a nozzle for exhausting pressure fluid within said one of said outside pressure chambers into said second chamber, an input port provided in said pilot body in opposite relation with said nozzle for introducing variable low pressure fluid into said second chamber, a generally flat thin film formed of a high tensile strength material disposed in said second chamber to partition the same axially, whereby said thin film is displaced into and out of contact with the outlet of said nozzle in accordance with variation of fluid pressure introduced through said input port into said second chamber so as to change the fluid pressure in said one of outside pressure chambers to switch said valve mechanism.